A solid ink printer typically uses a solid ink that is melted and jetted onto an image receptor prior to being transferred and fixed (transfixed) onto the media. A printer as that term is used here could be any device using a print engine, including copiers, fax machines, printers, multi-function devices (MFDs) that can print, fax, copy and scan, etc. The image receptor may be referred to as a drum for convenience, with no intention of limiting the transfer surface to a drum configuration. The image receptor may be supported by a drum or a belt.
The transfix process may include pressure and/or heat to transfer the image and fix it onto the media. Generally, a roller supplies the transfixing pressure in the nip. The nip is the region in which the image receptor and media come into contact to transfer the image. High-speed printers generally require controlled high pressures, generally in the range of about 550 pounds per square inch (approximately 250 kg/in2) to more than 2000 psi (approx. 900 kg/in2) depending on the particular solid ink compositions employed, the size of the recording medium, desired print quality (e.g., draft, final), applied heat, and the like.
Typically, pre-tensioned springs provide the pressure or load of the roller against the image receptor in the nip. A motor or other retracting means retracts the roller from the nip or extends the roller into the nip, against the tension of the spring(s) created by either of compression or extension of the spring from its resting state.
Tensioned springs generally deliver a slightly fluctuating roller load depending on variations in paper, device component run-out, etc. Pre-loaded springs may be unresponsive to dynamic mechanical aspects of the transfixing step. Using springs also requires more complicated manufacturing processes and result in bulkier products. Highly tensioned spring elements within a printing device chassis may potentially be dangerous to assembly and/or repair personnel. Inability to vary the force load based upon image content and print mode may cause the roller to run under more than necessary pressure all of the time, reducing roller life and increasing power consumption.